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Capacitor with 105 degree celsius ?

Discussion in 'Electronic Basics' started by mowhoong, Apr 8, 2005.

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  1. mowhoong

    mowhoong Guest

    Capacitor with a range of 105 Celsius & life 8000 hours? I am curious to know
    who will design a circuit put under such high temp. & only last for eight thousend
    hours, other component like plastic will also deform due to high temp.Do you think
    it make sense ? Can any person know the reason. Thanks.
     
  2. PeteS

    PeteS Guest

    I assume you are wondering why someone might specify such a part ( T >=
    105C, MTBF 8000 hrs)

    There are many places we routinely put electronic equipment where the
    ambient temperature can reach those levels (although we prefer them not
    to).

    One example is in aircraft - if there's circuitry near the leading wing
    edges of a modern jet aircraft, the temperature might easily attain
    100C (friction between the external air and the wing cause the heating)
    and we do have circuitry there - slat sensors for example. There are
    few circuits that don't require a capacitor (for bypassing / filtering)
    somewhere. You have obviously found one that is going into a harsh
    environment.

    On another note, the temperature within a box stuffed with electronic
    equipment is going to rise above external ambient - the only question
    is how much.

    The spec limit for most military parts is usually -55C to +125C,
    incidentally.

    Cheers

    PeteS
     
  3. tlbs

    tlbs Guest

    Another application for high(er) temperature components is the
    automotive industry. Inside of an automobile computer module, on a hot
    day, under the hood (bonnet) the ambient temperature can reach 65C.
    Then, if the automobile is started, some of the semiconductor junctions
    can quickly reach 85C or higher with the surrounding components heating
    up almost as high.

    A properly designed system would rarely use components that were only
    rated for the maximum stressors (temperature, voltage, etc.).
    Components are generally de-rated, so that 105C capacitor might be used
    in such an automotive application.

    BTW, I design space and military systems and we have to use components
    rated for -55C to +125C almost exclusively. Some of the semiconductors
    are rated for even higher temperatures.
     
  4. John Fields

    John Fields Guest

     
  5. Lord Garth

    Lord Garth Guest

    Besides the heat of drilling, what is the temperature at say 4000 feet?
     
  6. mowhoong

    mowhoong Guest

    Thanks for your reply, I remenber i dementle one of the branded hair dryer,
    i found a simple circuit with a E.capacitor hide inside the heater coil.
    The reason that the capacitor would not burn out due to a motor fan turn
    on when ever you switch on the hair dryer.How ever i will not design such
    like this with high risk if the motor fan slower than before due to some
    problum like the grease dry out in the motor bearing, a agree with me ?
     
  7. John Fields

    John Fields Guest

     
  8. mowhoong

    mowhoong Guest

    Hi John.
    What kind of Downhole equipment is? you will expect the solder tin melt when it
    reach 187 C. do you mean the electronic circuit board in the downhole ?
     
  9. John Fields

    John Fields Guest

     
  10. Lord Garth

    Lord Garth Guest

    The temperature below the sea bed is way cold!!! I expected it to start
    getting
    hot but then the first site wasn't drilling too deep ... < 600 meters below
    the
    sea bed.
     
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